ABSTRACT
Introduction This study aimed to investigate the clinical features and vaccine effectiveness of patients with the SARS-CoV-2 wild-type strain and the Delta variant. Methods We retrospectively evaluated patients with the SARS-CoV-2 wild-type strain and the Delta variant. Results The Delta-variant group showed a higher infection rate in minors, who had higher incidence of anosmia or dysgeusia and shorter incubation period. Unvaccinated patients had a 15.59-fold higher risk of severe classification than vaccinated patients. The viral clearance time was significantly shorter in the Delta-variant group. Conclusions The Delta-variant group show higher transmissibility, and vaccination reduces the incidence of severe classification and promotes viral clearance.